Notre-Dame basilica restoration costs soar to $100 million as work reveals hidden damage

The restoration of Montreal's Notre-Dame basilica will cost nearly $100 million — double the estimate from just two years ago — as workers discover structural damage that wasn't visible until they started the deep work inside.

Launched in 2017, the project began with the facades, requiring replacement of many stones on the twin towers. The West Tower work is complete, but its twin remains scaffolded. Inside, conservators are now working in the jubé — the upper gallery — retouching ceilings with faded colours and filling gaps where plaster has fallen.

Michel Issa, chief of the Fabrique de la paroisse Notre-Dame, said the "tant qu'à y être" surprises keep multiplying. "Everything we tell you today can change in a year. We make discoveries continuously every time we lean on a section or element to work on," he said. Mathieu Verreault, the basilica's operations director, added that teams had to change four times more stones than planned on the West Tower — a pattern likely to repeat on the East Tower. "The more we work, the more we discover things," he said.

The 2024 estimate of $50 million focused mainly on exterior work. The new total reflects a comprehensive evaluation of interior scope and external pressures like inflation. The Fabrique, which received just $1 million in public support, is now running a fundraising campaign targeting $50 million. The nonprofit launched a "Sponsor a Stone" program allowing donors to inscribe virtual messages on building stones.

The basilica marks its 200th anniversary in 2029, creating time pressure. "In about 8 to 9 years, we've done 20% of the work. We can't afford to wait 30 years to do the rest, or there will definitely be degradation," Issa said.